Touch sensitive devices have become popular as input devices to computing systems due to their ease and versatility of operation as well as their declining price. A touch sensitive device can include a touch screen formed from a transparent touch sensor panel and a display device. The display device, such as a liquid crystal display (LCD), can be positioned partially or fully behind the touch sensor panel or integrated with the touch sensor panel so that a touch sensitive surface of the touch sensor panel can cover at least a portion of the viewable area of the display device. The touch sensitive device can allow a user to perform various functions using a finger, stylus, or other object to touch or hover over the touch sensor panel at a location often dictated by a user interface (UI) being displayed by the display device. In general, the touch sensitive device can recognize a touch or proximity (hover) event and the position of the event on the touch sensor panel, and the computing system can then interpret the event in accordance with the display appearing at the time of the event, and thereafter can perform one or more actions based on the event.
Touch sensor panels can be designed to provide the largest active area (touch sensitive area, or touch sensitive display area when used in touch screens) practical, and to provide the clearest display practical when used in touch screens (i.e., provide a display experience that minimizes optical artifacts caused by touch sensor panel structures). Accordingly, narrow bezels surrounding a touch screen can be advantageous because they can increase touch screen real estate and keep devices compact. In addition, routing touch sensor panel electrodes to border areas and making necessary connections and crossovers outside of the active area can be advantageous to reduce the number of layers, dissimilar materials, and crossovers of those dissimilar materials in the active area and increase optical uniformity.
Although touch screens with conventional aspect ratios have become commonplace as the main input mechanism for many handheld devices, utilizing touch screens in other areas of the device, such as those areas requiring a high aspect ratio (e.g., where the touch screen length is much larger than the width), can present challenges to the goals of maximizing touch screen real estate and display clarity. For example, long, thin touch screens with high aspect ratios can result in numerous long routing traces being formed outside the active area of the touch screen, creating wide, undesirable bezels and limiting the amount of real estate available for the touch screen. To counteract the formation of wide bezels, the routing traces can be made thinner, but narrower trace widths and spacing can require higher process accuracy and uniformity control, which can increase processing complexity and cost. Furthermore, narrow traces widths and spacing can cause high trace line resistances, larger cross-coupling, and the like. In addition, high aspect ratio touch sensor panels can present issues for structures within the active area. For example, high aspect ratio touch screens can require long lengths of conductive material within the active area, and can contain layers, materials and structures that can lead to increased panel thickness, physical defects, manufacturing process steps/time, cost, parasitic capacitance, and structural failures during operation, and also to degraded touch sensing performance and optical uniformity.